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Picture for Corrosion Fatigue and Chloride-Induced Stress Corrosion Cracking in Sulfur Recovery Units
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Corrosion Fatigue and Chloride-Induced Stress Corrosion Cracking in Sulfur Recovery Units

Product Number: 51324-20691-SG
Author: Saud I Al Otaibi; Mohamud Farah
Publication Date: 2024
$40.00
Sulfur Recovery units (SRUs) are widely used in the oil and gas industry to recover sulfur from refined products and acid gas waste from the natural gas process. This involves routing acid gas rich in hydrogen sulfide through a reaction furnace to produce molten sulfur in a thermal Claus reaction. Central to the operation of the SRUs is the Sulfur storage pit, which is an underground high depth structure used to temporarily store sulfur product before shipment. Sulfur pits contain a range of critical equipment and piping, such as sulfur product pumps and steam coils.The pumps are crucial for shipping the sulfur product, while the steam coils are used for maintaining the molten sulfur temperature between 270-280 °F to prevent solidification and higher sulfur viscosity. Consequently, any impact to the integrity of this equipment impacts the unit’s operational efficiency or worse, leads to total unit shutdown. This equipment is susceptible to a range of damage mechanisms resulting from both operational conditions, such as sulfuric acid corrosion and environmental cracking, resulting from steam leakage and ground water seepage respectively. This paper investigates sulfuric acid corrosion and corrosion fatigue — in sulfur pumps — resulting from the synergistic effects of both dynamic loading and chloride-induced pitting corrosion. The steam coils in the pit were also found to suffer from both sulfuric acid corrosion and chloride stress corrosion cracking. These damage mechanisms were determined following extensive metallurgical analysis of samples recovered from the pit. Furthemore, laboratory compositional analysis from various samples collected from the pumps and the pits showed significant quantity of sodium chloride, resulting from ground water ingress alongside corrosion, and cementitious products, such as iron sulfide, quartz – SiO2 and iron sulfate. These findings, alongside sample results of the post-inspection findings for the sulfur recovery unit pit and equipment, will be highlighted and discussed. Effective mitigations, including the use of permanent dewatering, will also be discussed.
Picture for Corrosion Fatigue Performance of Materials in Delayed Cokers and Coker Blowdown Piping System
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Corrosion Fatigue Performance of Materials in Delayed Cokers and Coker Blowdown Piping System

Product Number: 51324-20618-SG
Author: Haixia Guo; Millar Iverson; Simon Yuen; Sudeep Bohra; Liu Cao
Publication Date: 2024
$40.00
Picture for Fatigue Loading of Test Specimens with Galvanically Induced Corrosion Damage Provides New Insight to Guide Fracture Mechanics Modeling
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Fatigue Loading of Test Specimens with Galvanically Induced Corrosion Damage Provides New Insight to Guide Fracture Mechanics Modeling

Product Number: 51324-20989-SG
Author: Thomas Curtin; Sharon Mellings; Ivan Karayan; Robert Adey; Joe Indeck
Publication Date: 2024
$40.00
Airframe structural components commonly experience galvanic damage at dissimilar metal connections following deterioration of insulating sealants or breakdown in coating protection systems. Of particular concern is the often-hidden corrosion damage that occurs inside fastener holes. Aggressive electrolytes can develop in these occluded spaces leading to the formation of multiple crack initiation sites and a compromise in the structural integrity of the component. To investigate this type of damage, laboratory testing was undertaken to evaluate fatigue life in AA 7075-T651 dog-bone specimens that included side holes fitted with CFRP inserts. The CFRP insert was used to introduce galvanic damage under thin film atmospheric corrosion conditions but removed prior to actual fatigue testing. Fatigue tests were conducted under constant amplitude loading, at R-ratios of 0.05, 0.6, and 0.89, in both air and 4.5M NaCl solution. Using a three-dimensional, fatigue crack growth (FCG) program, BEASY, complex crack propagation path evolution, and transition from surface flaw to through-crack was accurately represented. By selecting appropriate crack growth kinetics, the environmental effects on fatigue life were quantitatively determined for different modeling scenarios. Fractographic images of crack initiating features (corrosion pits, constituent particle clusters) were used to guide the location and sizing of initial flaws. Fatigue crack growth kinetic data, collected in both air and NaCl solution, was used to drive crack growth simulations. Modeling scenarios included the propagation of both single dominant flaws and multiple interacting flaws; the FCG life was evaluated for each case. This modeling work provides new insight for understanding how advanced fracture mechanics modeling capability can be used to improve life prediction of corroded components.